Telephony.



No. 792,691. PATENTED JUNE 20, 1905. E. A. BUBLL.

TELEPHONY.

APPLICATION FILED MAY 9, 1904.

mtneases." g g Z Ednarflalfizwll by 5 his .flltorneg UNTTEE STATES Patented June 20, 1905.

PATENT OEETQE.

EDWARD A. BUELL, OF DEKALB, ILLINOIS, ASSIGNOR TO SELECTIVE SIGNAL & TELEPHONE MANUFACTURING CO., OF SYCAMORE, ILLI- NOIS, A CORPORATION OF ILLINOIS.

TELEPHONY.

SPECIFICATION forming part of Letters Patent No. 792,691, dated June 20, 1905.

Application filed May 9, 1904. Serial No. 207,196.

To t uh/0m (1'15 may concern:

Be it known that I, EDWARD A. BUELL, a citizen of Canada, residing at Dekalb, in the county of Delralb and State of Illinois, have invented a certain new and useful Improvement in Telephony, of which the followingis a full, clear, concise, and exact description,reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to telephony, and is particularly adapted to that class of telephone systems wherein a single telephone-line is equipped with a plurality of subscribers stations, between any two of which conversation may be carried on without interference from any of the remaining subscribers stations or between any one of which and a substation of a totally distinct line conversation may be held without interference from any of the subscribers stations elsewhere connected with the telephone-circuit.

My invention relates particularly to the electromagnetic apparatus employed at the substations and controlled from the exchange whereby the selective and secrecy functions of the switching mechanism at the substations are very effectively and economically promoted, my invention enabling the employment of a single electromagnetic appliance adapted to set, release. and lock the switch parts, according to the desires of the operator.

I will explain my invention more fully by reference to the accompanying drawings, illustrating the preferred embodiment thereof, in which- Figure 1 illustrates a party telephone-line and so much of an apparatus at an exchange as is necessary to an understanding of my invention. Fig. 2 is a front view showing the relation of the coils and armature. Fig. 3 is a view on line a a/ of Fig. 1 of the electromagnetic portion of the structure.

Like parts are indicated by similar characters of reference throughout the different figures.

At the exchange I have indicated line-jacks 1 and 2 of normally independent telephonelines, there being a cord connecting apparatus for uniting independent telephone-lines in conversation, such cord connecting apparatus including an answering-plug 3 and a connecting-plug 4, which cord-circuit has the usual associate apparatus, including, among other things, (not shown,) an operators telephone outfit 5, an operators ringing-generator 6, a listening-key 7, and a ringing-key 8, there being provided a common actuating-lever 9, whereby the springs of the listening-key may be pressed against the operators telephoneterminals and whereby the springs of the ringing-key may be removed from their normal contacts and brought into engagement with the alternate contacts which constitute the ultimate terminals of the ringing-generator 6. Both of the alternate contacts of the ringing-key 8 are thus used when the bells to be rung by the generator are in metallic connection only with the telephone-lines.

I have indicated grounded signal receivers or bells 10 at the substations, which are connected'with the sleeve side of the party telephone-line 11, and I hence preferably provide a supplemental key 12, which is operated to limit the current emanating from the generator to the sleeve side of the telephone-line, the circuit being completed by way of the grounded alternate contact of the key 12 and the grounded bells. I, however, do not wish to be limited in all embodiments of my invention to the use of the grounded bells. I have indicated upon the party telephone-line three stations A, B, and C, though the number of stations connected with the line may be varied. The various stations are connected in multiple or bridge between the sides of the party-line, station A being included in such a bridge 13 14:. Station B has a bridge-path 15 16, while station C has a bridge-path 17 18. I prefer the bridge arrangement, as the element of impedance is so largely removed, though I do not wish to be limited to such an arrangement. The apparatus at station E is illustrated in detail. The apparatus of the other stations is preferably similar thereto. At station B, I have illustrated as one type of substation outfit a gravity telephone switchhook 19, a telephone-receiver 20 to be supported thereby, and a transmitter 21 of any preferred form, all of these instrumentalities being well understood by those skilled in the art, the switch-hook serving when in engagement with its normal contact through the agency of the telephone-receiver when supported to include the signal-bell in circuit and to cut out the telephone receiver and transmitter. I have indicated the well-known magneto-generator at the substation B; but I do not Wish to be limited to the use of magneto-generators at subscribers stations. The magneto-generator 22 when operated serves to release the shutter of the line-indicator 23, which in this particular instance is grounded and is normally in connection with the sleeve side of the party-line and the generator by way of the long spring of the line-jack 1 and the contact engaging said spring when the jack is free of a plug. In order that the current from the generator 22 may be sent in sufficient volume over the line to operate the line-indicator, the bell 10 is preferably made of very high resistance-for example, one thousand ohmswhich, however, is not too great to permit a fraction of the current to be diverted from the circuit containing the lineindicator through the bell to have the same operated at the calling-station, said bell being in shunt relation with the generator.

Both of the branches l5 and 16 may be subject to the electrical control had by the device of my invention. I have shown both sides and 16 to depend for their continuity upon a movable circuit-changer 24, desirably in the form of a ratchet-wheel, said ratchet-wheel carrying or operating two contact elements, each mechanically subdivided into two parts and 26 and 25 and 26 insulated therefrom, the parts of each set of elements being desirably constructed in two mechanically-separated but electrically connected elements which preferably are in the form of pins, though I do not wish to be limited to a contact element of this form. When the ratchet-wheel is in its initial or normal position, the elements 25 and 25 are in electrical connection with riders 27 27 which in turn are connected with and constitute parts of conductors 15 and 16. The elements 25 26 and 25 26 are separated by distance corresponding to distances between varying numbers of teeth at the different stations. The pins 25 and 25 at each station are what might be termed the normal or zero contact elements. The normal or zero elements 25 and 25 at each station are those contact elements which are always directly engaged by the riders 27 27 at all of the stations when the line is idle, which engagement is to be maintained when the line is'to be used as an ordinary party-line. The elements 26 26 may be termed the alternate contact elements and are those elements which are directly engaged with the riders 27 27 at any selected station when secrecy is desired and where selected signaling is to be practiced.

1n placing two subscribers on the same line in secret connection the operator intermittently actuates the electromagnetic apparatus, to be hereinafter described, for the purpose of shifting the circuit-changer 24 until the proper elements 26 26 (which, as hitherto set forth, are located differing distances away from the elements 25 25, according to the different stations) are brought into direct engagement with the riders 27 27 at the stations between which the secret connection is to be established. For example, station B indicates the second station upon the line, station C may indicate the third'station, and station A the first. At station A the pins 25 25 and 26 26' preferably have no tooth intervening. At station B the pins 25 25 and 26 26 have one tooth intervening, and at station C the pins 25 25 and 26 26 have two teeth intervening. To'connect station B with station (I, for example, the operator shifts the circuit-changer 24 two steps and then locks the same by mechanism to be set forth and shifts the circuitchanger 24 at station C another step, the said latter circuit-changer having previously been operated two steps in setting the apparatus at station B. It will be apparent to those skilled in the art that at all other stations the riders 27 27 are not in connection with those portions of the circuit-changers or wheels 24 that are electrically connected with the teeth 25 25 and 26 26, thereby opening the branches that depend for their continuity upon the engagement of the riders 27 27 with one or the other of the teeth 25 25 and 26 26. Thus both terminals of the telephone-receivers are disconnected from the line by being included in open circuit.

Having described one form of circuit-changing apparatus that may be employed in connection with my invention for governing the association of the subscribers stations with the partyline,I will nowdescribe my improved electromagnetic mechanism that is employed for effecting the operation of the said circuitchangers and will thereafter describe the switching apparatus at the exchange that is employed for operating the electromagnetic mechanism.

The wheels 24 are provided with coil-springs 28, by which when released by my magnetic actuating mechanism they are restored to initial positions where the contacts 25 25 engage the riders 27 27, the wheel 24 at station B (as at other stations) having thereon an arm 29, engaging a stop 30 to limit the return of the wheel. My improved electromagnetic mechanism has two spools or helices 31 32, preferably unprovided with a magnetic yoke, but having a common armature 33 centrally pivoted between the poles of the spools. The magnet of this mechanism is provided with a permanent magnet 34 to induce polarity of the same sign in the poles of the coils 31 32 that are presented to the armature 33 and to also polarize said armature. One of the Windings, as the winding 31, when included in circuit with the source of direct current tends to reinforce or increase the field at the pole of said winding 31 opposed to the armature 33, while the other winding is reversely wound to secure an opposite effect. By proper circuit connections the armature 33 may be caused to oscillate in a clockwise direction or in a counter-clockwise direction, as desired, or the armature may be bodily moved toward both opposing poles. The pivot for the armature is desirably provided upon a plunger 34, that has splined engagement with a housing 35, the parts 34 and 35 being desirably of non-magnetic metal. The pivot is preferably subdivided into two parts 36 37, the bracket 38, carried by the plunger 34, serving to support these pivots, the parts of the bracket that immediately support the pivots being preferably of ear-like formation, the armature 33 being interposed between these cars. Some suitable means may be provided for normally maintaining the armature away from both poles. I have indicated retractile springs 39 39 and adjustable back-stops 40, against which the armature is normally held by said retractile springs. The work to be performed by this electromagnetic mechanism may be accomplished by some suitable extension of the armatureas, for example, the rod or lever 41, projecting atright angles to the armature. In the present instance this electromagnetic mechanism has been applied to the peculiar form of secrecy and cut-out switching mechanism that has been hitherto described. The first function that this mechanism has to perform is the movement of the circuit-changing wheel 24 from engagement with its normal stop 30, to which end the armature 33 is attracted toward both of the magnet-poles opposing the same. This movement causes the dog 42, pivotal] y supported upon the arm 41, to advance the ratchet-wheel against the force of the coil-spring 28. The next function of the magnetic mechanism is to lock the circuit-changing wheel 24 in the selected position. This is accomplished by causing a rotation of the free end of the arm 41 downwardly by the counter-clockwise movement of the armature, so that the cam 44 may be pressed against the plunger 45 against the force of a coil-spring 46, whereby a pin 47, carried upon the wheel, may be forced into engagement with the hooked end of the plunger 45, which desirably is sufficiently yielding so as to permit the said hooked end to pass the pin 47, but which is of such a nature as to secure a locking engagement until the engagement between the pin and plunger has been broken. As the dog 42 moves the wheel in a counter-clockwise direction, the locking pawl or dog 48, having a fixed axis of rotation at its rear end, prevents the return of the wheel, which locking-pawl is pivoted upon a link 49, that may be moved back and forth in an inclined groove 50 in an enlarged end of the arm 41. It will be seen how effectively the two elements 48 and 45 serve to define the position of the wheel 24, the first preventing movement by the spring and the second when set preventing movement of the arm 41 and the armature 33 in a direction parallel to the cores of the magnet. It will be understood that the plunger 45 need only be operated at the station where the circuit-wheel 24 is to be moved the lesser number of times in effecting telephonic communication between that station and another where the circuit-wheel is to be moved a greater number of times. Such movement of the circuit-wheels, as is understood, is only to be had when secrecy is desired, so that the subscribers may call each other or the exchange without the aid of my improved electromagneticmechanism. hen it is desired to release a given circuit-wheel, the armature 33 is moved in a clockwise direction, whereby the dog 48 is lifted, permitting the spring 28 to move the wheel 24 back against its stop 30. When this movement occurs, the plunger 45 is free from the pin 47, whereupon the spring 46 restores said plunge'r to its initial or normal position.

The various operations of the magnetic circuit-controlling mechanism at each station may be governed by a battery 51, divided into two parts for some purposes, but all of which are used for the purpose of effecting the bodily reciprocation of the armature 33. The extreme poles of this battery are connected with the alternate contacts of the selecting-key 52, the springs whereof are thrust against said alternate contacts when selection at the substations is to be effected. The lever of the key 52 is preferably maintained toward the right, while the wedge end of the lever 9 is moved to and fro to intermittently effect the connection of the springs of the key 8 with their alternate contacts that are in electrical connection with the springs of the key 52, whereby the battery 51 is intermittently in bridge of the party-line, for the purpose specified. I have found by experiment that onehalf of each battery will not be suflicient to efiect bodily reciprocation of the armature 33, but will effect the operative energization of one coil of the magnet only. The left-hand end of the battery 51 is preferably employed for operatively energizing the coils 31 32 independently, depending upon the direction that the current from this portion of the battery is impressed upon said windings, such current being insufficient to operatively energize both windings in a manner to effect the bodily reciprocation of the armature 33, but sufiiciently increasing the magnetization at one of the poles opposed to the armature 33 and weakening the other to secure the oscillation of said armature in one direction or the other, according to the direction of the current. The poles of this half of the battery are connected with the springs of the key 53 when said springs are thrust against their alternate contacts that are connected with said poles, the plunger 54L being employed for effecting this movement of said springs. Current from the left half of the battery 51 is thereupon caused to flow over the line in a direction to reinforce the magnetization of the core of the winding 31 and to oppose or weaken the magnetization of the core of the winding 32, whereupon the armature 33 is rocked in a counter-clockwise direction to eifect a depression of the plunger 45 into engagement with the pin 4L7. When it is desired to restore the individual mechanisms to theirinitial positions at the substations, the locking-key 53 is released and the springs of the releasing-key 55 are spread apart by their associate lever, whereupon the left-hand half of the battery 51 has its connection with the line reversed, causing a reversal of the conditions just described respecting the energi- Zation of the cores of the windings 31 32, forcing the armature 33 to turn in a clockwise direction and thereupon elevate the dog 48 to permit the spring 28 to restore each circuit-wheel against its stop 30.

It is obvious that changes may readily be made in the apparatus of my invention herein shown and particularly described without departing from the spirit of my invention, and I do not, therefore, Wish to be limited to the precise construction and arrangement shown; but,

Having thus described my invention, I claim as new and desire to secure by Letters Patentl. The combination with a party telephone line, of selective switching mechanism at each of the subscribers stations on said line, an electromagnetic appliance including a single operating-electromagnet exerting setting and locking action upon said switching mechanism, the windings of said electromagnetic appliances at the different stations being in parallel, and switching mechanism in association with the line for operating said electromagnetic mechanism, substantially as described.

2. The combination with a party telephoneline, of selective switching mechanism at each of the subscribers stations on said line, an electromagnetic appliance including a single operatingelectromagnet exerting setting, locking and releasing action upon said switching mechanism, the windings of said electromagnetic appliances at the different stations being in parallel, and switching mechanism in association with the line for operating said electromagnetic mechanism, substantially as described.

3. The combination with a party telephoneline, of selective switching mechanism at each of the subscribers stations on said line, an electromagnetic appliance including a single operating-electromagnet exerting releasing and locking action upon said switching mechanism,the windings of said electromagnetic appliances at the different stations being in parallel, and switching mechanism in association with the line for operating said electromagnetic mechanism, substantially as described.

4:. The combination with a telephone-line I extending from a plurality of subscribers stations to an exchange, of selective switching mechanism at each of the subscribers stations on said line, an electromagnetic appliance including a single operating-electromagnet at each of said stations, exerting setting and locking action upon said switching mechanism, the windings of said electromagnetic devices at the different stations being in parallel, and switchingmechanism at the exchange governing said electromagnetic mechanism, substantially as described.

5. The combination with a telephone-line extending from a plurality of subscribers stations to an exchange, of selective switching mechanism at each of the subscribers stations on said line, an electromagnetic appliance including a single operating-electromagnet at each of said stations, exerting setting, locking and releasing action upon said switching mechanism, the windings of said electromagnetic devices at the different stations being in parallel, and switching mechanism at the exchange governing said electromagnetic mechanism, substantially as described.

6. The combination with a telephone-line extending from a plurality of subscribers stations to an exchange, of selective switching mechanism at each of the subscribers stations on said line, an electromagnetic appliance including a single operating-electromagnet at each of said stations, exerting releasing and locking action upon said switching mechanism, the windings of said electromagnetic devices at the different stations being in parallel, and switching mechanism at the exchange governing said electromagnetic mechanism, substantially as described.

In witness whereof I hereunto subscribe my name this 6th day of May, A; D. 190 i.

EDWARD A. BUELL.

Witnesses:

W. L. POND, JOHN A. DOWDALL. 

